The present invention relates to cutting tools or drill bits, and more particularly, to cutting tools which are used in hammering, percussive, or rotary boring or drilling applications in concrete, aggregate, masonry or the like material.
When drilling concrete, aggregate or the like materials, generally three different types of cutting tools or bits are used. These bits can be defined as hammer bits, percussive bits, and rotary masonry bits. In a true hammer bit, the bit is placed into a driver which includes a hammer which is sequentially and repetitiously moved toward and away from the bit. This hammering action hammers the bit. While the bit is being hammered, the bit continues to either passively or actively rotate. Thus, this type of cutting would be synonymous with using a chisel and hitting it with a hammer. Also, the driver may include a rotational feature where the bit is hammered and actively rotated.
In percussive drilling, the drive includes a chuck which is associated with stepping cam surfaces on gears which are rotated and, at the same time, moved up and down within the driver. Thus, the entire chuck mechanism rotates and moves up and down during the cutting process.
A rotary masonry bit is positioned into a driver which provides only a rotary movement. Thus, the rotary masonry bit does not move up and down and just rotates to cut at the concrete or aggregate.
Cutting tools in these three fields require different parameters for each type of application. In hammer and percussive bits, which utilize a chiseling action, the tip cutting angle, which provides tip strength, debris elimination and a cutting or rake face are a primary concern. Likewise, in rotary masonry drilling, which uses purely rotary movement, the cutting or rake face, debris clean out and cutting angle are also of primary importance. However, all of these elements are interrelated to provide an optimum cutting tool or drill bit to drill concrete, aggregate and the like materials.
Existing hammer and percussive cutting tools ordinarily include carbide insert tips with cutting edges which have large obtuse included angles as well as a negative rake face at large acute angles. Thus, the tip has been utilized to chisel and rotate to drill or bore into the concrete material. The rotary masonry bits ordinarily use a rake face on the bit so that when it is rotated, it will bore through the concrete material.
Further, when the carbide tips are formed, the carbide powder is laterally pressed into a mold to form the tip. This tip is inserted directly and welded or brazed onto a tool shank. Thus, this is the art accepted way to form current design tools or bits.